Some computer peripheral buses support daisy-chaining of devices, such that you can plug one device into your computer, a second device into the first, and a third into the second, all with the same kind of cable, and the computer can use them all. These include HP-IL (which is actually connected in
a ring), HP-IB/GPIB, SCSI, FireWire, and Thunderbolt.

However, you'll have a hard time finding a modern computer that supports any of those but Thunderbolt, and a hard time finding a peripheral of a given type that supports any of those at all. Most peripherals are only available for USB, and USB inherently doesn't support daisy-chaining. What USB does support, though, is hubs. You plug a USB hub into your computer, and then you can plug more than one USB peripheral into your computer by plugging them into the hub, using only one port on the computer, using up the hub's ports instead. This is fine, but it would be more convenient in a lot of situations if you didn't need a separate device that performs no useful function itself and only provides extra ports.

So I suggest that common USB peripherals such as hard drives and printers be made with USB hubs inside. They'd still only connect to the computer using a single USB cable, and the actual device (hard drive or printer) would be internally connected to one of the hub's ports. Many USB keyboards actually already do this, but their hubs are invariably low-speed and low-power, not even adequate for a flash drive, only a mouse. What I'm proposing, where the hub-hosting device would have its own power supply, would mitigate these limitations by allowing the hub to be powered and High Speed or even SuperSpeed (whichever the hub-hosting device needs for itself). It would also provide extra USB ports at times when you aren't using an external keyboard that has a USB hub built in, or need better ports than those.

Many LCD monitors already have built-in USB hubs, but that is not an implementation of this idea because those monitors are not themselves USB devices and do not communicate with the host computer over USB; those are just monitors and USB hubs sharing power supply and enclosure but nothing else. The significance of this difference is that the main cable you connect the monitor to the computer with is not a USB cable; you have to connect a second cable to use the hub. (Yes, there are USB monitors, but I don't think any of those has an integrated USB hub. And yes, ADC ran USB and video over the same cable, but that's obsolete (sadly), and none of the modern display connections seems to do that.)

Ironically, I thought of this just now because I wanted to plug my phone in to charge (not even wanting an extra USB port for data), but the only free USB port on my laptop was on the right side where the cable would get in the way of mousing, and I didn't have a USB power adapter handy, so I wished I could plug it into my external hard drive that's on the left side instead, but then after I wrote up this whole idea, I realized something I never realized until now even I've been using my laptop at this same desk with the same configuration of two external monitors that have integrated USB hubs for months, namely that I don't need to actually be using the hubs to connect devices to my computer for them to be able to supply power, so I just plugged my phone into one of the monitors and now it's happily charging. But I probably would have thought to plug my phone into a monitor sooner had I, a few weeks ago, followed through with my plan to connect those monitors' USB hubs to my computer, one plugged into the other so only one cable would go to my laptop, because then I would have those hubs' ports in my mind as 'usable USB ports'.